New κ3-PNN′- and κ4-PNN′O- polydentate ligands: Synthesis, coordination and structural studies

Article abstract of DOI:10.1016/j.ica.2011.09.045

The three-step synthesis of new mixed P/N/N′/O-donor ligands C ₆H₃(OH){2-NHC(O)CH₂NCHC₆H ₄PPh₂}(4-CH₃) 3a·HH and C ₆H₄(OH){3-NHC(O)CH₂NCHC₆H ₄PPh₂} 3b·HH, by Schiff base condensation of the 1° amines C₆H₃(OH){2-NHC(O)CH₂NH ₂}(4-CH₃) 2a or C₆H₄(OH){3-NHC(O) CH₂NH₂} 2b with C₆H₄(CHO)(2-PPh ₂) in refluxing EtOH, is described. Reaction of 1 equiv. of 3a·HH or 3b·HH with MCl₂(cod) (M = Pt, Pd; cod = cycloocta-1,5-diene) affords the κ²-PN-chelate complexes MCl₂(3a·HH) (M = Pd 4a; M = Pt 4b) and MCl ₂(3b·HH) (M = Pt 4c). The dichlorometal(II) complexes 4d and 4e, bearing instead a pendant 4-phenolic group, were similarly prepared (in >90% yield). Chloro-bridge cleavage of [Pd(μ-Cl)(η³-C ₃H₅)]₂ with 3a·HH or 3b·HH gave the monocationic κ²-PN-chelate complexes [Pd(η³- C₃H₅)(3a·HH)]Cl 5a or [Pd(η³-C ₃H₅)(3b·HH)]Cl 5b, respectively. Elimination of cod, and single CH₃ protonation, from Pt(CH₃) ₂(cod) upon reaction with 1 equiv. of 3a·HH or 3b·HH in C₇H₈ at room temperature afforded the neutral complexes C₆H₃(OH){2-NC(O)CH₂NCHC₆H ₄PPh₂Pt(CH₃)}(4-CH₃) 6a and C ₆H₄(OH){3-NC(O)CH₂NCHC₆H ₄PPh₂Pt(CH₃)} 6b, respectively bearing a monoanionic (3a·H^- or 3b·H^-) κ³-PNN′-tridentate ligand. Amide and phenol deprotonation were readily achieved, using KO^tBu as base, to give high yields of the κ⁴-PNN′O-tetradentate complexes C₆H ₃(O){2-NC(O)CH₂NCHC₆H₄PPh ₂Pd}(4-CH₃) 7a and C₆H₃(O){2-NC(O) CH₂NCHC₆H₄PPh₂Pt}(4-CH₃) 7b bearing the dianionic ligand 3a^2-. All new compounds have been characterised by multinuclear NMR, FTIR, mass spectroscopy and microanalysis. Single crystal X-ray studies have been performed on compounds 1b·1.5CH₂Cl₂, 3b·HH·0.5Et ₂O, 6b·CHCl₃ and 7b·0.5Et₂O.

Full text of DOI:10.1016/j.ica.2011.09.045

Inorganica Chimica Acta 379 (2011) 115–121
Contents lists available at SciVerse ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
New j3-PNN0- and j4-PNN0O-polydentate ligands: Synthesis, coordination
and structural studies
⇑
Mark R.J. Elsegood, Noelia M. Sanchez-Ballester, Martin B. Smith
Department of Chemistry, Loughborough University, Loughborough, Leics LE11 3TU, UK
a r t i c l e i n f o
a b s t r a c t
The three-step synthesis of new mixed P/N/N0/O-donor ligands C6H3(OH){2-NHC(O)CH2N@CHC6H4
PPh2}(4-CH3) 3aꢀHH and C6H4(OH){3-NHC(O)CH2N@CHC6H4PPh2} 3bꢀHH, by Schiff base condensation of
the 1° amines C6H3(OH){2-NHC(O)CH2NH2}(4-CH3) 2a or C6H4(OH){3-NHC(O)CH2NH2} 2b with
C6H4(CHO)(2-PPh2) in refluxing EtOH, is described. Reaction of 1 equiv. of 3aꢀHH or 3bꢀHH with MCl2(cod)
Article history:
Received 22 July 2011
Received in revised form 20 September
2011
Accepted 21 September 2011
Available online 1 October 2011
(M = Pt, Pd; cod = cycloocta-1,5-diene) affords the
j
2-PN-chelate complexes MCl2(3aꢀHH) (M = Pd 4a;
M = Pt 4b) and MCl2(3bꢀHH) (M = Pt 4c). The dichlorometal(II) complexes 4d and 4e, bearing instead a pen-
dant 4-phenolic group, were similarly prepared (in >90% yield). Chloro-bridge cleavage of [Pd(l-Cl)
Keywords:
Coordination modes
Metallocycles
P ligands
Late-transition metals
X-ray crystallography
(
g
3-C3H5)]2 with 3aꢀHH or 3bꢀHH gave the monocationic
j -
2-PN-chelate complexes [Pd(g3
C3H5)(3aꢀHH)]Cl 5a or [Pd(
g
3-C3H5)(3bꢀHH)]Cl 5b, respectively. Elimination of cod, and single CH3 proton-
ation, from Pt(CH3)2(cod) upon reaction with 1 equiv. of 3aꢀHH or 3bꢀHH in C7H8 at room temperature
afforded the neutral complexes C6H3(OH){2-NC(O)CH2N@CHC6H4PPh2Pt(CH3)}(4-CH3) 6a and
C6H4(OH){3-NC(O)CH2N@CHC6H4PPh2Pt(CH3)} 6b, respectively bearing a monoanionic (3aꢀHꢁ or 3bꢀHꢁ)
j3-PNN0-tridentate ligand. Amide and phenol deprotonation were readily achieved, using KOtBu as base,
to give high yields of the j4-PNN0O-tetradentate complexes C6H3(O){2-NC(O)CH2N@CHC6H4PPh2Pd}(4-
CH3) 7a and C6H3(O){2-NC(O)CH2N@CHC6H4PPh2Pt}(4-CH3) 7b bearing the dianionic ligand 3a2ꢁ. All
new compounds have been characterised by multinuclear NMR, FTIR, mass spectroscopy and microanaly-
sis. Single crystal X-ray studies have been performed on compounds 1bꢀ1.5CH2Cl2, 3bꢀHHꢀ0.5Et2O,
6bꢀCHCl3 and 7bꢀ0.5Et2O.
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
to a square-planar metal(II) centre. All new compounds are struc-
turally supported by a combination of spectroscopic and crystallo-
Organometallic and coordination complexes of tridentate and
tetradentate ligands continue to attract wide interest for the
diverse ligating capabilities, sensing, magnetic and luminescent
properties and catalytic applications. Various donor atom combi-
nations have been documented in the literature and, in many cases,
contain at least one phosphorus donor centre. A range of different
donor atom combinations have been reported for tridentate
ligands including amongst others: P2B [1], P2C [2], P2Si [3], P2N
[4], P2O [5], PC2 [6], PN2 [7], PNO [8], PNS [8c] and PS2 [9]. Further-
more, while examples of symmetric tetradentate systems are rela-
tively common and include, for example, P2N2 [10], O2N2 [11] or
S2N2 [12], nonsymmetric tetradentate ligands are considerably
more unusual and include P3C [13], P3Si [14], P3N [15], PN3 [16],
PN2O [17] and As2PN [18]. Herein we describe the synthesis of
two new potentially tetradentate ligands bearing a PNN0O donor
set combination. We demonstrate, given the correct spatial donor
atom orientation, that all four donor centres can readily coordinate
graphic techniques.
2. Experimental
2.1. Materials
Standard Schlenk techniques were used for the synthesis of
C6H3(OH){2-NHC(O)CH2N@CHC6H4PPh2}(4-CH3) 3aꢀHH and C6H4
(OH){3-NHC(O)CH2N@CHC6H4PPh2} 3bꢀHH whilst all other reac-
tions were carried out in air using previously distilled solvents un-
less otherwise stated. The compounds C6H4(CHO)(2-PPh2) [19],
MCl2(cod) (M = Pt, Pd; cod = cycloocta-1,5-diene) [20] and Pt(CH3)2
(cod) [21] were all prepared according to known procedures. All
other chemicals were obtained from commercial sources and used
directly without further purification.
2.2. Instrumentation
⇑
Infrared spectra were recorded as KBr pellets on either a Perkin–
Elmer System 2000 (4000–400 cmꢁ1 range) or a Spectrum 100S
Corresponding author. Tel.: +44 0 1509 222553; fax: +44 0 1509 223925.
E-mail address: m.b.smith@lboro.ac.uk (M.B. Smith).
0020-1693/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2011.09.045

116
M.R.J. Elsegood et al. / Inorganica Chimica Acta 379 (2011) 115–121
(4000–250 cmꢁ1 range) Fourier-Transform spectrometer. 1H NMR
spectra (400 MHz) were recorded on a Bruker DPX-400 FT spec-
trometer with chemical shifts (d) in ppm to high frequency of
Si(CH3)4 and coupling constants (J) in Hz. 31P{1H} NMR spectra were
recorded on a Bruker DPX-400 FT spectrometer with chemical shifts
(d) in ppm to high frequency of 85% H3PO4. NMR spectra were mea-
sured in CDCl3 or (CD3)2SO at 298 K. Elemental analyses (Perkin–
Elmer 2400 CHN or Exeter Analytical, Inc. CE-440 Elemental
Analyzers) were performed by the Loughborough University Ana-
lytical Service within the Department of Chemistry. Mass spectra
were recorded within the Department of Chemistry at Loughbor-
ough University and by the EPSRC National Mass Spectrometry Ser-
vice at Swansea University. Compounds 4a and 4b were analysed
(Thermofisher LTQ Orbitrap XL instrument) by nano-electrospray
(nano-ESI) in a positive ionisation mode using CH2Cl2 as primary
solvent.
1H), 9.16 (s, 1H), 8.54 (d, 1H), 7.72–6.84 (m, 18H), 4.24 (s, 2H),
2.15 (s, 3H) ppm. FTIR: 3314, 1654 cmꢁ1. ESMS: m/z 453 [M+H].
Anal. Calc. for C28H25N2O2P: C, 74.31; H, 5.58; N, 6.19. Found: C,
74.05; H, 5.49; N, 6.11%. Similarly C6H4(OH){3-NHC(O)CH2N@
CHC6H4PPh2} 3bꢀHH was prepared in 53% isolated yield. Selected
data: 31P [(CD3)2SO]: –13.6 ppm. 1H: 9.82 (d, 1H), 9.43 (s, 1H),
8.84 (d, 1H), 8.02–6.90 (m, 16H), 6.49 (ddd, 1H), 4.23 (s, 2H)
ppm. FTIR: 3243, 3104, 1661 cmꢁ1. EIMS: m/z 438 [M]. Anal. Calc.
for C27H23N2O2P: C, 73.95; H, 5.30; N, 6.39. Found: C, 73.79; H,
5.29; N, 6.45%.
2.3.4. Preparation of C6H3(OH){2-NHC(O)CH2N@CHC6H4PPh2PdCl2}
(4-CH3) (4a), C6H3(OH){2-NHC(O)CH2N@CHC6H4PPh2PtCl2}(4-CH3)
(4b), C6H4(OH){3-NHC(O)CH2N@CHC6H4PPh2PtCl2}(4c), C6H4(OH) {4-
NHC(O)CH2N@CHC6H4PPh2PdCl2} (4d) and C6H4(OH){4-NHC(O)
CH2N@CHC6H4PPh2PtCl2} (4e)
2.3. Syntheses
To a CH2Cl2 (20 mL) solution of PdCl2(cod) (0.064 g, 0.22 mmol)
was added 3aꢀHH (0.101 g, 0.22 mmol) to give a yellow solution.
After stirring the solution for 15 min a yellow solid formed and the
volume then reduced under vacuum to ꢂ1–2 mL. Addition of diethyl
ether (25 mL) further aided precipitation. The solid 4a was collected
by suction filtration and dried in vacuo. Yield: 0.136 g, 96%. Com-
pounds 4b–4e were prepared similarly using either PtCl2(cod) or
PdCl2(cod). Selected data for 4a: 31P [(CD3)2SO]: 33.1 ppm. FTIR:
3318, 3261, 1701, 1644, 1625, 1594 cmꢁ1. FTMS + p NSI: m/z 557
[Mꢁ2HCl+H+]. Anal. Calc. for C28H25N2O2PPdCl2: C, 53.39; H, 4.01;
N, 4.45. Found: C, 53.51; H, 4.21; N, 4.13%. Selected data for 4b
2.3.1. Preparation of C6H3(OH){2-NHC(O)CH2NHCO2Bz}(4-CH3) (1a)
and C6H4(OH){3-NHC(O)CH2NHCO2Bz} (1b)
To a THF (100 mL) solution of carbobenzyloxyglycine (5.054 g,
0.024 mol) was added, in quick succession, C6H3(OH)(2-NH2)
(4-CH3) (2.980 g, 0.024 mol) and dicyclohexylcarbodiimide, DCC
(5.346 g, 0.026 mol). The solution was stirred for approx. 4 h dur-
ing which time a white solid formed. The solid was removed by fil-
tration and the filtrate evaporated to dryness under reduced
pressure. The THF solvent was replaced by ethyl acetate (100 mL)
and petroleum ether (b.p 40–60 °C, 100 mL) to afford 1a which
was collected by suction filtration and dried in vacuo. Yield:
5.544 g, 73%. Selected data: 1H [(CD3)2SO]: 9.65 (s, 1H), 9.08 (s,
1H), 7.73–6.72 (m, 8H), 5.08 (s, 2H), 3.85 (d, 2H), 2.19 (s, 3H)
ppm. FTIR: 3344, 3286, 3258, 1721, 1659 cmꢁ1. FTMS: m/z 315
[M+H]. Anal. Calc. for C17H18N2O4: C, 64.95; H, 5.78; N, 8.91. Found:
C, 65.00; H, 5.89; N, 9.35%. Similarly, C6H4(OH){3-NHC(O)CH2NH-
CO2Bz} 1b was prepared in 68% yield. Selected data: 1H [(CD3)2SO]:
9.84 (s, 1H), 9.40 (s, 1H), 7.55–6.94 (m, 9H), 6.45 (dd, 1H), 5.06 (s,
2H), 3.79 (d, 2H) ppm. FTIR: 3392, 3313, 3224, 1704, 1692,
1674 cmꢁ1. FTMS: m/z 301 [M+H]. Anal. Calc. for C16H16N2O4: C,
63.99; H, 5.38; N, 9.33. Found: C, 64.18; H, 5.64; N, 9.33%.
1
1
(90% yield): 31P [(CD3)2SO]: 9.1 ppm, JPtP 3476 Hz; 3.8 ppm, JPtP
1
3753 Hz; 1.4 ppm, JPtP 3230 Hz. FTIR: 3389, 3266, 1667, 1631,
1596 cmꢁ1
. FTMS + p NSI: m/z 683 [M–Cl]. Anal. Calc. for
C28H25N2O2PPtCl2ꢀEt2O: C, 48.49; H, 4.46; N, 3.54. Found: C, 49.09;
H, 3.81; N, 4.03%. Selected data for 4c (97% yield): 31P [(CD3)2SO]:
1
1
1
8.8 ppm, JPtP 3479 Hz; 4.0 ppm, JPtP 3771 Hz; 1.5 ppm, JPtP
3204 Hz. FTIR: 3349, 3203, 1662, 1635, 1592 cmꢁ1. Anal. Calc. for
C27H23N2O2PPtCl2ꢀ0.5Et2O: C, 46.97; H, 3.81; N, 3.78. Found: C,
46.71; H, 3.51; N, 3.92%. Selected data for 4d (93% yield): 31P
[(CD3)2SO]: 37.9 ppm. FTIR: 3406, 1668, 1644, 1598 cmꢁ1. ESMS:
m/z 581 [M–Cl]. Anal. Calc. for C27H23N2O2PPdCl2ꢀ0.25CH2Cl2: C,
51.37; H, 3.73; N, 4.40. Found: C, 51.23; H, 3.81; N, 4.07%. Selected
1
data for 4e (94% yield): 31P [(CD3)2SO]: 9.8 ppm, JPtP 3487 Hz;
2.3.2. Preparation of C6H3(OH){2-NHC(O)CH2NH2}(4-CH3) (2a) and
C6H4(OH){3-NHC(O)CH2NH2} (2b)
1
1.8 ppm, JPtP 3952 Hz. FTIR: 3210, 1670, 1636, 1593 cmꢁ1. ESMS:
m/z 669 [M–Cl]. Anal. Calc. for C27H23N2O2PPtCl2: C, 46.03; H, 3.30;
A mixture of 1a (1.002 g, 3.19 mmol), Pd (10% on C) (0.268 g),
EtOH (50 mL) and cyclohexene (2.5 mL) was refluxed for 15 min.
After cooling, the mixture was filtered and the solution evaporated
to dryness under reduced pressure to afford 2a. Yield: 0.502 g, 87%.
Selected data: 1H [(CD3)2SO]: 7.81 (d, 1H), 6.56–6.46m, 2H), 3.03 (s,
2H), 1.99 (s, 3H) ppm. FTIR: 3421, 3352, 3255, 3060, 3028,
1648 cmꢁ1. ESMS: m/z 181 [M+H]. Anal. Calc. for C9H12N2O2: C,
59.98; H, 6.73; N, 15.55. Found: C, 60.19; H, 6.84; N, 15.53%. The
related compound C6H4(OH){3-NHC(O)CH2NH2} 2b was also pre-
pared (91% isolated yield). Selected data: 1H [(CD3)2SO]: 9.65 (br,
1H), 7.23–6.43 (m, 4H), 3.23 (s, 2H) ppm. FTIR: 3345, 3331, 3296,
1673 cmꢁ1. ESMS: m/z 167 [M+H]. Anal. Calc. for C8H10N2O2: C,
57.82; H, 6.08; N, 16.86. Found: C, 58.21; H, 6.37; N, 16.09%.
N, 3.98. Found: C, 46.09; H, 3.76; N, 3.83%.
2.3.5. Preparation of [C6H3(OH){2-NHC(O)CH2N@CHC6H4PPh2Pd(g3
C3H5)}(4-CH3)]Cl (5a) and [C6H4(OH){3-NHC(O)CH2N@CHC6H4
-
PPh2Pd(
To a solution of [Pd(
g
3-C3H5)}]Cl (5b)
l-Cl)(g
3-C3H5)]2 (0.037 g, 0.10 mmol) in
CH2Cl2 (5 mL) was added 3aꢀHH (0.092 g, 0.20 mmol) to afford a
yellow solution. After stirring for 1 h the solution was concentrated
under reduced pressure to ꢂ1–2 mL and diethyl ether (10 mL)
added. The yellow solid 5a was collected and dried in vacuo. Yield:
0.113 g, 88%. Selected data for 5a: 31P (CDCl3): 24.3 ppm. 1H: 8.88
(s, 1H), 8.71 (s, 1H), 7.81–6.87 (m, 18H), 5.80 (q, 1H), 5.40 (s, 2H),
4.00 (br), 3.07 (br), 2.24 (s, 3H) ppm. FTIR: 3434, 3222, 3160, 1656,
1629 cmꢁ1. ESMS: m/z 599 [M–Cl]. Anal. Calc. for C31H30N2O2PPdCl:
C, 58.68; H, 4.78; N, 4.42. Found: C, 58.34; H, 4.79; N, 4.44%. Se-
lected data for 5b (96% yield): 31P (CDCl3): 24.0 ppm. 1H: 8.58 (s,
1H), 8.33 (s, 1H), 7.77–6.47 (m, 19H), 5.68 (q, 1H), 5.13 (s, 2H),
3.88 (br), 2.81 (br) ppm. FTIR: 3378, 3248, 3196, 3140, 1683,
2.3.3. Preparation of C6H3(OH){2-NHC(O)CH2N@CHC6H4PPh2}(4-CH3)
(3aꢀHH) and C6H4(OH){3-NHC(O)CH2N@CHC6H4PPh2} (3bꢀHH)
A suspension of 2a (0.399 g, 2.21 mmol) and C6H4(CHO)(2-PPh2)
(0.667 g, 2.30 mmol) in absolute EtOH (40 mL) was refluxed, under
a N2 atmosphere, for approx. 4 h. After cooling to r.t., the volume
was reduced to ꢂ10 mL under reduced pressure, cooled to 0 °C
and the solid collected by suction filtration. The solid 3aꢀHH was
washed with a small portion of EtOH and dried in vacuo. Yield:
0.608 g, 61%. Selected data: 31P [(CD3)2SO]: –9.6 ppm. 1H: 9.78 (s,
1633, 1608 cmꢁ1
. ESMS: m/z 585 [M–Cl]. Anal. Calc. for
C30H28N2O2PPdClꢀ0.25CH2Cl2: C, 56.53; H, 4.48; N, 4.36. Found: C,
56.20; H, 4.49; N, 3.93%.

M.R.J. Elsegood et al. / Inorganica Chimica Acta 379 (2011) 115–121
117
2.3.6. Preparation of C6H3(OH){2-NC(O)CH2N@CHC6H4PPh2Pt(CH3)}
(4-CH3) (6a), C6H4(OH){3-NC(O)CH2N@CHC6H4PPh2Pt(CH3)} (6b) and
C6H4(OH){4-NC(O)CH2N@CHC6H4PPh2Pt(CH3)} (6c)
557 [M]. Anal. Calc. for C28H23N2O2PPdꢀH2O: C, 58.49; H, 4.39; N,
4.87. Found: C, 58.36; H, 4.08; N, 4.82%. Selected data for 7b: 31P
(CDCl3): 6.9 ppm, 1J(PtP) 3374 Hz. 1H: 8.25, 3J(PtH) 97.1 Hz (s,
1H), 8.07 (d, 1H), 7.71–6.50 (m, 16H), 5.03 (s, 2H), 2.21 (s, 3H)
ppm. FTIR: 1635 (CO), 1610, 1587 cmꢁ1. ESMS: m/z 647 [M]. Anal.
Calc. for C28H23N2O2PPt: C, 52.09; H, 3.60; N, 4.34. Found: C, 51.96;
H, 3.74; N, 3.99%.
To the solids Pt(CH3)2(cod) (0.039 g, 0.12 mmol) and 3aꢀHH
(0.054 g, 0.12 mmol) was added toluene (1 mL) to afford an initial
yellowsolutionwhichlaterturnedorange. Afterstandingfor approx.
2 d, a yellow crystalline solid 6a formed which was collected by suc-
tion filtration, washed with petroleum ether (b.p. 60–80, 5 mL) and
dried. Yield: 0.050 g, 65%. The j3-PNN0-tridentate complexes 6b
(84% yield) and 6c (86% yield) were prepared similarly. Selected data
for 6a: 31P (CDCl3): 13.3 ppm, 1J(PtP) 3852 Hz. 1H: 8.40 (3J(PtH) 43.9,
s, 1H), 7.57–6.66 (m, 17H), 4.80 (s, 2H), 2.08 (s, 3H), 0.00 (2J(PtH)
2.4. X-ray crystallography
Slow evaporation of a THF/Et2O solution of 1b gave suitable
crystals whereas crystals of 3bꢀHH were obtained by vapour diffu-
sion of Et2O into a CH2Cl2/EtOH solution. For 6b and 7b, suitable
crystals were obtained by vapour diffusion of Et2O into a CHCl3/
MeOH (or CH2Cl2) solution. Details of the data collection parame-
ters and crystal data for 1bꢀ1.5CH2Cl2, 3bꢀHHꢀ0.5Et2O, 6bꢀCHCl3
and 7bꢀ0.5Et2O are given in Table 1. Measurements for
3bꢀHHꢀ0.5Et2O, 6bꢀCHCl3 and 7bꢀ0.5Et2O were made on a Bruker
SMART 1000 (Apex II for 1bꢀ1.5CH2Cl2) CCD diffractometer using
71.5 Hz, d, 3H) ppm. FTIR: 3422, 1636, 1616, 1590, 1568 cmꢁ1
.
ESMS: m/z 662 [M]. Anal. Calc. for C29H27N2O2PPt: C, 52.64; H,
4.12; N, 4.24. Found: C, 52.09; H, 4.12; N, 4.12%. Selected data for
6b: 31P [(CD3)2SO]: 12.3 ppm, 1J(PtP) 3736 Hz. 1H: 9.22 (s, 1H), 9.06
(3J(PtH) 41.0, s, 1H), 8.09–6.44 (m, 18H), 4.91 (s, 2H), 0.00 (2J(PtH)
70 Hz, d, 3H) ppm. FTIR: 3368, 3230, 1635, 1611, 1567 cmꢁ1. ESMS:
m/z 648 [M]. Anal. Calc. for C28H25N2O2PPtꢀ0.75C7H8: C, 55.72; H,
4.37; N, 3.92. Found: C, 55.37; H, 4.39; N, 4.06%. Selected data for
6c: 31P [(CD3)2SO]: 12.2 ppm, 1J(PtP) 3689 Hz. 1H: 9.07 (s, 1H),
8.11–6.75 (m, 18H, arom. H), 4.91 (s, 2H), 0.00 (2J(PtH) 72.0 Hz, d,
3H) ppm. FTIR: 1628, 1573 cmꢁ1. ESMS: m/z 648 [M+H]. Anal. Calc.
for C28H25N2O2PPt: C, 51.93; H, 3.90; N, 4.33. Found: C, 51.64; H,
3.72; N, 3.77%.
graphite monochromated radiation from a sealed tube Mo K
a
source. Narrow frame -scans were employed and intensities were
x
corrected semi-empirically for absorption, based on symmetry-
equivalent and repeated reflections. The structures were solved
by direct methods and refined on F2 values for all unique data by
full-matrix least squares. All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were constrained in a riding mod-
el with Ueq set to 1.2 Ueq of the carrier atom (1.5 Ueq for methyl
hydrogen) except for NH and OH coordinates in 1bꢀ1.5CH2Cl2 and
3bꢀHHꢀ0.5Et2O which were freely refined. In each structure the sol-
vent of crystallisation was badly disordered and modelled by the
Platon Squeeze procedure [22]. In 3bꢀHHꢀ0.5Et2O, disorder in one
of the phenyl rings [C(22)–C(27)] was modelled with restraints
on geometry and displacement parameters; major component
occupancy = 58.4(11)%. In 7bꢀ0.5Et2O, the hydrogen atoms in the
CH3 groups [C(28) and C(56)] were disordered (50/50). Programs
used included Bruker AXS APEX II and SMART [23] for diffractometer
control and SAINT for frame integration [24], Bruker SHELXTL [25] for
2.3.7. Preparation of C6H3(O){2-NC(O)CH2N@CHC6H4PPh2Pd}(4-CH3)
(7a) and C6H3(O){2-NC(O)CH2N@CHC6H4PPh2Pt}(4-CH3) (7b)
A yellow CH3OH (2 mL, HPLC grade) suspension of 4a (0.099 g,
0.16 mmol) was treated with tBuOK (0.040 g, 0.36 mmol). The
resulting purple suspension was stirred for 1 h, the solid 7a col-
lected by filtration and washed with a small portion of CH3OH.
Yield: quantitative. Compound 7b was prepared similarly in 92%
yield. Both 7a and 7b could be recrystallised from CH2Cl2/Et2O/
hexanes. Selected data for 7a: 31P (CDCl3): 20.3 ppm. 1H: 7.97 (s,
1H), 7.93 (s, 1H), 7.64–7.34 (m, 14H), 6.48 (d, 2H), 4.96 (s, 2H),
2.16 (s, 3H) ppm. FTIR: 1640 (CO), 1606, 1583 cmꢁ1. ESMS: m/z
Table 1
Crystallographic data for 1bꢀ1.5CH2Cl2, 3bꢀHHꢀ0.5OEt2, 6bꢀCHCl3 and 7bꢀ0.5OEt2.
Compound
1bꢀ1.5CH2Cl2
3bꢀHHꢀ0.5OEt2
6bꢀ0.5OEt2
7bꢀ0.5OEt2
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C16H16N2O4ꢀ1.5CH2Cl2
C27H24N2O2Pꢀ0.5OEt2
C28H25N2O2PPtꢀCHCl3
C28H23N2O2PPtꢀ0.5OEt2
427.70
476.51
766.93
682.60
orthorhombic
Fdd2
17.772(5)
77.05(2)
4.7521(12)
triclinic
monoclinic
P21/c
10.1906(6)
16.8627(10)
17.5250(10)
triclinic
ꢀ
ꢀ
P1
P1
8.5606(13)
10.0060(15)
16.348(2)
87.437(2)
76.095(2)
71.080(2)
1285.0(3)
2
11.8789(4)
14.6793(5)
15.8954(5)
82.1451(5)
76.8028(5)
85.4477(5)
2669.89(15)
4
b (Å)
c (Å)
a
(°)
b (°)
97.3012(10)
c
(°)
V (Å3)
6507(3)
16
2987.1(3)
4
Z
k
0.71073
0.71073
0.71073
0.71073
T (K)
150(2)
1.746
0.594
plate, pale yellow
0.42 ꢃ 0.14 ꢃ 0.03
2.35–25.00
2864
150(2)
1.232
0.137
rod, colourless
0.99 ꢃ 0.08 ꢃ 0.04
2.15–27.50
10909
150(2)
1.705
5.048
tablet, yellow
0.11 ꢃ 0.10 ꢃ 0.04
1.68–29.01
25926
150(2)
1.698
5.347
block, red
0.36 ꢃ 0.35 ꢃ 0.11
1.81–28.96
23700
Dcalc [mgm3]
Absorption coefficient (mmꢁ1
Crystal habit and colour
Crystal size (mm3)
h Range (°)
)
Reflections collected
Independent reflections
1618 [Rint = 0.0335]
1286
5654 [Rint = 0.0283]
3498
7213 [Rint = 0.0508]
4830
12353 [Rint = 0.0177]
10504
Reflections with F2 > 2
r
(F2)
Completeness (%)
99.6
99.0
100.0
99.3
Number of parameters
208
0.0634, 0.1805
341
0.0548, 0.1451
309
0.0355, 0.0707
613
0.0207, 0.0537
Final Ra, Rw
b
P
P
a
R = ||Fo| ꢁ |Fc||/ |Fo|.
P
P
wR2 = [ [w(F2o ꢁ F2c )2]/ [w(F2o )2]]1/2
.
b

118
M.R.J. Elsegood et al. / Inorganica Chimica Acta 379 (2011) 115–121
structure solution, refinement, and molecular graphics and local
programs.
amines 2a and 2b. Characterising data for 1a–2b are given in
Section 2.
The X-ray structure of 1bꢀ1.5CH2Cl2 has been determined
(Fig. 1) and confirms the successful incorporation of the
{3-NHC(O)CH2NHCO2Bz} group. A 2-dimensional structure (SI-
FIG1) propagating in the ac plane was obtained through a combina-
tion of strong (amino)NHꢀꢀꢀO(amide) [N(1)ꢀꢀꢀO(2’) 2.777(5) Å, N(1)–
H(1A)ꢀꢀꢀO(2’) 156(5)°; N(2)ꢀꢀꢀO(3’’) 2.901(6) Å, N(2)–H(2)ꢀꢀꢀO(3’’)
149(5)°] and (hydroxyl)O–HꢀꢀꢀO(amide) [O(1)ꢀꢀꢀO(3’’’) 2.870(5) Å,
3. Results and discussion
3.1. Ligand synthesis
The nonsymmetric ligands 3aꢀHH and 3bꢀHH (Scheme 1) were
synthesised, starting from commercially available 2-amino-4-
methylphenol or 3-aminophenol, using an adapted method for
the synthesis of ligands with N2O2 and N3O donor sets [26]. Hence
reaction of the appropriate aminophenol with carbobenzyloxygly-
cine and a slight excess of DCC in THF for 4 h gave 1a or 1b in 73%
and 68% yields, respectively. Hydrogenolysis of 1a or 1b with Pd/C
(10%) and cyclohexene in refluxing EtOH afforded the primary
0
1
O(1)–H(1)ꢀꢀꢀO(3’’’) 162(7)°; symmetry operators = z + 1 4; x ꢁ
,
4
1
ꢁy + 1 4, z ꢁ 4; ‘‘ = x, y, z + 1, ’’’ = x + 1 4, ꢁy + 1 4] intermolecular H-
bonding interactions.
Schiff base condensation of 2a or 2b with C6H4(CHO)(2-PPh2) in
refluxing EtOH gave, after simple workup, the phosphino(imines)
3aꢀHH or 3bꢀHH in 61% and 53% yields, respectively. Schiff base
Scheme 1. Preparation of 1a–2b, 3aꢀHH and 3bꢀHH.

M.R.J. Elsegood et al. / Inorganica Chimica Acta 379 (2011) 115–121
119
Fig. 1. X-ray structure of 1b. The CH2Cl2 solvent of crystallisation and all hydrogen atoms except those on N(1), N(2) and O(1) have been removed for clarity.
condensation was readily ascertained by 31P and 1NMR spectros-
copy. Compounds 3aꢀHH and 3bꢀHH adopt an E-(anti-)configura-
tion as previously found for other phosphino(imines)
[16a,17a,27] and further supported, in the case of 3bꢀHH, by a sin-
gle crystal X-ray study. The X-ray structure of 3bꢀHHꢀ0.5OEt2
(Fig. 2) has been determined with the geometry around P(1) being
essentially distorted tetrahedral with C–P–C angles in the range
101.08(11)°–103.30(11)°. The P(1) group faces both the N(1)/N(2)
donor atoms in contrast to our previous work [17a] in which, for
the 2-positioned –OH isomer, the O(2)/N(1)/N(2) groups point
away from the –PPh2 substituent. Various H-bonding interactions
exist including an intramolecular N(1)ꢀꢀꢀH(2)–N(2) H-bond
[N(1)ꢀꢀꢀN(2) 2.668(2) Å, N(1)ꢀꢀꢀH(2)–N(2) 117(2)°] and an intermo-
lecular O(1)ꢀꢀꢀH(2A’)–O(2’) [O(1)ꢀꢀꢀO(2’) 2.687(2) Å, O(1)ꢀꢀꢀH(2A’)
the geometric flexibility of both new ligands. Phosphino(imines)
are well known ligands which coordinate in a
2-PN-chelating
manner at various transition metal centres [27]. Treatment of
2-PN-
j
3aꢀHH or 3bꢀHH with MCl2(cod) (M = Pt, Pd) afforded the
j
chelate complexes MCl2(3aꢀHH) (M = Pd 4a; M = Pt 4b) and
MCl2(3bꢀHH) (M = Pt 4c) in excellent yields (>90%). For NMR com-
parison purposes, the isomeric 4-phenol positioned metal(II) com-
plexes 4d and 4e were also prepared. Furthermore we successfully
synthesised the mononuclear cationic complexes [Pd(g
3-C3H5)
(3aꢀHH)]Cl 5a and [Pd(
g
3-C3H5)(3bꢀHH)]Cl 5b from the room tem-
perature reaction of [Pd(
l
-Cl)(g
3-C3H5)]2 and 3aꢀHH or 3bꢀHH in
CH2Cl2. The 31P{1H} NMR spectra of 4a, 4d, 5a and 5b all showed
downfield phosphorus chemical shifts [d(P) 33.1; 37.9; 24.3 and
24.0 ppm, respectively]. For 4b, 4c and 4e, in (CD3)2SO solution,
1
0
O(2’) 176(3)°; symmetry operator = ꢁx+3, ꢁy + 1, ꢁz + 1] H-bond
three PtII species were observed with JPtP coupling constants typ-
linking molecules into head-to-tail dimer pairs (SIFIG2) with an
R22(16) motif [28]. Intermolecular OꢀꢀꢀHꢁO hydrogen bonded 1D-
chains were previously observed by us when the phenolic group
is located in the 4-position [17a].
ically in the range of 3204–3952 Hz suggesting possible coordina-
tion of one or both the NH/OH donor groups and formation of
cationic platinum(II) species in highly polar DMSO solvent media.
Other characterising data are given in Section 2.
Reaction of 3aꢀHH or 3bꢀHH with Pt(CH3)2(cod) in C7H8 at ambi-
ent temperature gave the neutral j3-PNN0-tridentate complexes 6a
and 6b in 65% and 84% yields, respectively. In the 31P{1H} NMR
spectra a single 31P resonance was observed at d(P) 13.3 (6a) and
3.2. Coordination studies
The reactivity of 3aꢀHH and 3bꢀHH towards PdII and PtII square
1
13.2 (6b) ppm with JPtP of approx. 3800 Hz. The 1H NMR spectra
planar metal centres was briefly investigated in order to ascertain
clearly confirmed the presence of one methyl bound ligand and
was further supported by the single crystal X-ray structure deter-
mination of 6bꢀCHCl3 (Fig. 3).
Complex 6b displayed an essentially square-planar geometry
around the PtII centre with bond angles in the range 81.07(15)°–
95.13(11)° (Table 2). The Pt(1)–N(1)–C(8)–C(7)–C(2)–P(1) six-
membered ring is essentially flat with Pt(1) and N(1) lying 0.456 Å
and 0.161 Å, respectively out of the plane defined by atoms C(8),
C(7), C(2) and P(1). For the five-membered ring, C(9) and N(1) are
0.025 Å and 0.024 Å, respectively out of the plane defined by atoms
Pt(1), N(1), C(9), C(10) and N(2). Dimer pairs are formed through
intermolecular OꢀꢀꢀH–O H-bonding [O(1)ꢀꢀꢀO(2A) 2.636(5) Å,
O(1)ꢀꢀꢀH(2A)–O(2A) 174°; symmetry operator A = ꢁx + 1, ꢁy, ꢁz]
generating an R22(16) ring motif [28].
t
Reaction of 4a or 4b with BuOK, in CH3OH, gave the neutral
complexes 7a and 7b in which j4-PNN0O-tetradendate coordina-
tion of 3a2ꢁ has occurred. For 7b, the 31P{1H} NMR spectrum
1
showed a reduction (ꢂ500 Hz) in JPtP coupling relative to the j3
-
PNN0-tridentate coordination observed in 6a. The X-ray structure
of 7bꢀ0.5Et2O has been determined (Fig. 4 and SIFIG3) with se-
lected bond lengths and angles given in Table 3. There are two mol-
ecules with very similar conformations in the asymmetric unit. The
Pt–P, Pt–N and Pt–O bond lengths are all broadly as anticipated
[17a,29]. Consistent with j4-PNN0O-tetradendate coordination is
the presence of one six- (PtPCCCN) and two five-membered
(PtNCCN and PtNCCO) chelate rings. The three metallocyclic con-
formations in 7b can be described as follows: the Pt(1)–N(1)–
Fig. 2. X-ray structure of 3bꢀHH. The Et2O solvent of crystallisation and all
hydrogen atoms except those on N(2) and O(2) have been removed for clarity.

120
M.R.J. Elsegood et al. / Inorganica Chimica Acta 379 (2011) 115–121
Fig. 3. X-ray structure of 6b. The CHCl3 solvent of crystallisation and all hydrogen atoms except those on O(2) and O(2A) have been removed for clarity.
Table 2
Table 3
Selected bond lengths and angles for 6bꢀCHCl3.
Selected bond lengths and angles for 7bꢀ0.5OEt2.a
Bond length (Å)
Bond length (Å)
Pt(1)–P(1)
Pt(1)–N(1)
Pt(1)–N(2)
Pt(1)–O(2)
C(7)–N(1)
Pt(1)–P(1)
Pt(1)–N(1)
Pt(1)–N(2)
Pt(1)–C(1)
C(8)–N(1)
C(10)–O(1)
2.1828(13)
2.059(4)
2.062(4)
2.055(5)
1.283(6)
1.257(5)
2.2259(6) [2.2263(7)]
1.974(2) [1.972(2)]
1.989(2) [1.995(2)]
2.0010(17) [2.0103(19)]
1.285(3) [1.288(4)]
1.234(3) [1.228(3)]
C(9)–O(1)
Bond angle (°)
Bond angle (°)
P(1)–Pt(1)–C(1)
P(1)–Pt(1)–N(1)
P(1)–Pt(1)–N(2)
N(1)–Pt(1)–C(1)
N(1)–Pt(1)–N(2)
N(2)–Pt(1)–C(1)
91.24(15)
95.13(11)
175.86(10)
173.36(18)
81.07(14)
92.61(17)
P(1)–Pt(1)–O(2)
P(1)–Pt(1)–N(1)
P(1)–Pt(1)–N(2)
N(1)–Pt(1)–O(2)
N(1)–Pt(1)–N(2)
N(2)–Pt(1)–O(2)
97.95(5) [97.42(5)]
95.13(6) [95.60(7)]
177.71(6) [179.01(7)]
166.49(8) [166.92(8)]
83.42(8) [84.22(10)]
83.40(8) [82.74(9)]
a
Equivalent parameters for the second independent molecule are given in square
parentheses.
0.005 Å for Pt(1)–N(2)–C(10)–C(15)–O(2) for mol. 1; 0.06 Å and
0.008 Å for mol. 2].
4. Conclusions
In summary, we have shown that new multifunctionalised
phosphino(imines) containing predisposed NH/OH groups can be
prepared and shown to adopt various ligation modes at square pla-
nar metal centres such as PtII and PdII.
Acknowledgements
We are extremely grateful to Johnson Matthey for their kind
donation of precious metals and to the EPSRC National Mass Spec-
trometry Service at Swansea University for data collection.
Appendix A. Supplementary material
Fig. 4. X-ray structure of 7b. The Et2O solvent of crystallisation and all hydrogen
atoms have been removed for clarity.
CCDC 833456, 833457, 833458 and 833459 contain the supple-
mentary crystallographic data for 1bꢀ1.5CH2Cl2, 3bꢀHHꢀ0.5Et2O,
6bꢀCHCl3 and 7bꢀ0.5Et2O, respectively. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif. Supplementary data
associated with this article can be found, in the online version, at
doi:10.1016/j.ica.2011.09.045.
C(7)–C(6)–C(1)–P(1) ring is essentially flat with P(1) lying 0.40 Å
[or 0.27 Å for P(2)] out of the plane defined by atoms Pt(1), N(1),
C(7), C(6) and C(1), whereas both five-membered rings are effec-
tively planar [within 0.06 Å for Pt(1)–N(1)–C(8)–C(9)–N(2) and

M.R.J. Elsegood et al. / Inorganica Chimica Acta 379 (2011) 115–121
(c) M.R.J. Elsegood, A.J. Lake, M.B. Smith, Dalton Trans. (2009) 30;
121
References
(d) N.L. Fry, M.J. Rose, C. Nyitray, P.K. Mascharak, Inorg. Chem. 47 (2008)
11604;
(e) W.A. Chomitz, J. Arnold, Chem. Commun. (2007) 4797;
(f) J. Bennett, A.D. Rae, G. Salem, N.C. Ward, P. Waring, K. Wells, A.C. Willis, J.
Chem. Soc., Dalton Trans. (2002) 234.
[1] Y. Segawa, M. Yamashita, K. Nozaki, J. Am. Chem. Soc. 131 (2009) 9201.
[2] (a) P. O’Leary, C.A. van Walree, N.C. Mehendale, J. Sumerel, D.E. Morse, W.C.
Kaska, G. van Koten, R.J.M. Klein Gebbink, Dalton Trans. (2009) 4289;
(b) J. Choi, Y. Choliy, X. Zhang, T.J. Emge, K. Krogh-Jespersen, A.S. Goldman, J.
Am. Chem. Soc. 131 (2009) 15627;
(c) B.L. Dietrich, K.I. Goldberg, D.M. Heinekey, T. Autrey, J.C. Linehan, Inorg.
Chem. 47 (2008) 8583.
[3] (a) A. García-Camprubi, M. Martin, E. Sola, Inorg. Chem. 49 (2010) 10649;
(b) E. Morgan, D.F. MacLean, R. McDonald, L. Turculet, J. Am. Chem. Soc. 131
(2009) 14234;
[11] (a) K.J. Blackmore, N. Lal, J.W. Ziller, A.F. Heyduk, J. Am. Chem. Soc. 130 (2008)
2728;
(b) B. Saito, H. Egami, T. Katsuki, J. Am. Chem. Soc. 129 (2007) 1978;
(c) C. González-Arellano, A. Corma, M. Iglesias, F. Sánchez, Chem. Commun.
(2005) 1990.
[12] (a) A.R. Cowley, J.R. Dilworth, P.S. Donnelly, J.M. White, Inorg. Chem. 45 (2006)
496;
(b) P.J. Blower, T.C. Castle, A.R. Cowley, J.R. Dilworth, P.S. Donnelly, E. Labisbal,
F.E. Sowrey, S.J. Teat, M.J. Went, Dalton Trans. (2003) 4416.
[13] (a) M. Ciclosi, F. Estevan, P. Lahuerta, V. Passarelli, J. Pérez-Prieto, M. Sanaú,
Dalton Trans. (2009) 2290;
(b) M. Ciclosi, J. Lloret, F. Estevan, P. Lahuerta, M. Sanaú, J. Pérez-Prieto, Angew.
Chem., Int. Ed. 45 (2006) 6741.
[14] M.T. Whited, N.P. Mankad, Y. Lee, P.F. Oblad, J.C. Peters, Inorg. Chem. 48 (2009)
2507.
[15] M.T. Whited, E. Rivard, J.C. Peters, Chem. Commun. (2006) 1613.
[16] (a) S.E. Durran, M.R.J. Elsegood, S.R. Hammond, M.B. Smith, Inorg. Chem. 46
(2007) 2755;
(b) Y.K. Kim, S.J. Lee, K.H. Ahn, J. Org. Chem. 65 (2000) 7807.
[17] (a) S.E. Durran, M.R.J. Elsegood, S.R. Hammond, M.B. Smith, Dalton Trans. 39
(2010) 7136;
(b) G.A. Bogdanovic, A. Spasojevic´-de Biré, B.V. Prelesnik, V.M. Leovac, Acta
Crystallogr., Sect. C: Cryst. Struct. Commun. 54 (1998) 766.
[18] R.J. Doyle, G. Salem, A.C. Willis, J. Chem. Soc., Dalton Trans. (1997) 2713.
[19] J.E. Hoots, T.B. Rauchfuss, D.M. Roundhill, Inorg. Chem. 21 (1982) 175.
[20] (a) D. Drew, J.R. Doyle, Inorg. Synth. 13 (1972) 47;
(b) J.X. McDermott, J.F. White, G.M. Whitesides, J. Am. Chem. Soc. 98 (1976)
6521.
[21] E. Costa, P.G. Pringle, M. Ravetz, Inorg. Synth. 31 (1997) 284.
[22] A.L. Spek, Acta Crystallogr., Sect. A 46 (1990) C34.
[23] APEX II and SMART Programs for Diffractometer Control, Bruker AXS Inc.,
Madison, WI, 2006 and 2001.
[24] SAINT Software for CCD Diffractometers, Bruker AXS Inc., Madison, WI, 2001 and
2006.
[25] (a) G.M. Sheldrick, SHELXTL User Manual, Version 6.10, Bruker AXS Inc., Madison,
WI, 2000.;
(b) G.M. Sheldrick, Acta Crystallogr., Sect. A 64 (2008) 112.
[26] (a) M.R. Bermejo, A.M. González, M. Fondo, A. García-Deibe, M. Maneiro, J.
Sanmartin, O.L. Hoyos, M. Watkinson, New J. Chem. 24 (2000) 235;
(b) M.R. Bermejo, A.M. González, M. Fondo, M. Maneiro, M. Rey, M. Vázquez,
O.L. Hoyos, J.C. García-Monteagudo, Inorg. Chim. Acta 307 (2000) 106;
(c) O.L. Hoyes, M.R. Bermejo, M. Fondo, A. García-Deibe, A.M. González, M.
Maneiro, R. Pedrido, J. Chem. Soc., Dalton Trans. (2000) 3122.
[27] M.-H. Thibault, B.E.G. Lucier, R.W. Schurko, F.-G. Fontaine, Dalton Trans. (2009)
7701.
(c) D.F. MacLean, R. McDonald, M.J. Ferguson, A.J. Caddell, L. Turculet, Chem.
Commun. (2008) 5146.
[4] (a) L.C. Gregor, C.-H. Chen, C.M. Fafard, L. Fan, C. Guo, B.M. Foxman, D.G. Gusev,
O.V. Ozerov, Dalton Trans. 39 (2010) 3195;
(b) M. Feller, E. Ben-Ari, M.A. Iron, Y. Diskin-Posner, G. Leitus, L.J.W. Shimon, L.
Konstantinovski, D. Milstein, Inorg. Chem. 49 (2010) 1615;
(c) B. Askevold, M.M. Khusniyarov, E. Herdtweck, K. Meyer, S. Schneider,
Angew. Chem., Int. Ed. 49 (2010) 7566;
(d) J.I. van der Vlugt, J.N.H. Reek, Angew. Chem., Int. Ed. 48 (2009) 8832;
(e) D. Benito-Garagorri, L. Goncalo Alves, M. Puchberger, K. Mereiter, L.F.
Veiros, M.J. Calhorda, M. Deus Carvalho, L.P. Ferreira, M. Godinho, K. Kirchner,
Organometallics 28 (2009) 6902;
(f) A. Friedrich, R. Ghosh, R. Kolb, E. Herdtweck, S. Schneider, Organometallics
28 (2009) 708;
(g) N.D. Jones, P. Meessen, U. Losehand, B.O. Patrick, B.R. James, Inorg. Chem. 44
(2005) 3290.
[5] (a) A.E.W. Ledger, A. Moreno, C.E. Ellul, M.F. Mahon, P.S. Pregosin, M.K.
Whittlesey, J.M.J. Williams, Inorg. Chem. 49 (2010) 7244;
(b) G. Asensio, A.B. Cuenca, M.A. Esteruelas, M. Medio-Simón, M. Oliván, M.
Valencia, Inorg. Chem. 49 (2010) 8665;
(c) Q. Major, A.J. Lough, D.G. Gusev, Organometallics 24 (2005) 2492.
[6] C. Gracia, G. Marco, R. Navarro, P. Romero, T. Soler, E.P. Urriolabeitia,
Organometallics 22 (2003) 4910.
[7] (a) A. Picot, H. Dyer, A. Buchard, A. Auffrant, L. Vendier, P. Le Floch, S. Sabo-
Etienne, Inorg. Chem. 49 (2010) 1310;
(b) S.D. Phillips, J.A. Fuentes, M.L. Clarke, Chem. Eur. J. 16 (2010) 8002;
(c) S. Liu, R. Peloso, P. Braunstein, Dalton Trans. 39 (2010) 2563;
(d) M.R.J. Elsegood, A.J. Lake, M.B. Smith, Eur. J. Inorg. Chem. (2009) 1068;
(e) B.M. Schmiege, M.J. Carney, B.L. Small, D.L. Gerlach, J.A. Halfen, Dalton
Trans. (2007) 2547;
(f) C. Redshaw, V.C. Gibson, M.R.J. Elsegood, W. Clegg, Chem. Commun. (2007)
1951;
(g) A. Choualeb, A.J. Lough, D.G. Gusev, Organometallics 26 (2007) 5224.
[8] (a) O. del Campo, A. Carbayo, J.V. Cuevas, A. Muñoz, G. Garcia-Herbosa, D.
Moreno, E. Ballesteros, S. Basurto, T. Gómez, T. Torroba, Chem. Commun.
(2008) 4576;
(b) P. Raghavendra Kumar, S. Upreti, A.K. Singh, Polyhedron 27 (2008) 1610;
(c) J.D.G. Correia, A. Domingos, I. Santos, H. Spies, J. Chem. Soc., Dalton Trans.
(2001) 2245;
(d) J.D.G. Correia, A. Domingos, A. Paulo, I. Santos, J. Chem. Soc., Dalton Trans.
(2000) 2477;
[28] (a) M.C. Etter, J.C. MacDonald, J. Bernstein, Acta Crystallogr., Sect. B 46 (1990)
256;
(b) M.C. Etter, Acc. Chem. Res. 23 (1990) 120;
(c) J. Bernstein, R.E. Davis, L. Shimoni, N.-L. Chang, Angew Chem., Int. Ed. Engl.
34 (1995) 1555.
(e) P. Bhattacharyya, M.L. Loza, J. Parr, A.M.Z. Slawin, J. Chem. Soc., Dalton
Trans. (1999) 2917.
[9] (a) M. Doux, L. Ricard, P. Le Floch, N. Mézailles, Dalton Trans. (2004) 2593;
(b) V. Gómez-Benítez, S. Hernández-Ortega, D. Morales-Morales, Inorg. Chim.
Acta 346 (2003) 256.
[29] Y. Shimazaki, N. Arai, T.J. Dunn, T. Yajima, F. Tani, C.F. Ramogida, T. Storr,
Dalton Trans. 40 (2011) 2469.
[10] (a) A. Gondoh, T. Koike, M. Akita, Inorg. Chim. Acta 374 (2011) 489;
(b) C. Schotes, A. Mezzetti, J. Am. Chem. Soc. 132 (2010) 3652;